Vertical Substrate Coating with Piston and Vacuum
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Solution Overview
Problem
Existing methods for coating substrates with catalyst components in emissions control devices face challenges due to the narrow viscosity range of washcoat processing, which limits the types of substrates and viscosities that can be effectively coated, leading to variations in coating lengths and reduced precision.
Innovation Solution
A method and apparatus that allow for continuous introduction of a catalyst component liquid into the substrate's channels, using a piston to push the liquid against gravity, and applying a vacuum once the substrate is part-filled, enabling uniform coating over a wide range of viscosities without modifying the washcoat formulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pre-determined quantity of liquid component is dosed into a containment means and drawn into the support by pressure or vacuum, then substantially all of the quantity is retained within the support, but the method requires locating a containment means on top of the support and dosing procedures that add device complexity
Solution Approach 1:
The invention removes the containment means from the system entirely. Instead of using a containment means to hold and dose the liquid, the liquid is introduced directly into the substrate channels through the open ends, eliminating the need for separate containment equipment while maintaining reliable liquid delivery
Solution Approach 2:
The substrate itself serves as the containment structure through its channel network. The channels naturally guide and retain the liquid within the substrate matrix without requiring external containment means, allowing the substrate to perform both structural and liquid-holding functions
2Manufacturing precision
If the substrate is immersed into a bath of coating slurry and vacuum is applied to draw the slurry upwardly into channels, then the coating slurry is distributed within the channels, but the method requires rotating the substrate 180° and applying pressurized air which increases process time and complexity
Solution Approach 1:
The coating process is segmented into distinct phases: first introducing liquid to fill channels to a predetermined level, then applying vacuum to draw additional liquid in. This segmentation allows precise control over coating depth and uniformity without requiring substrate rotation or multiple processing steps
Solution Approach 2:
The substrate is pre-positioned vertically with channels oriented upward before liquid introduction. This preliminary positioning eliminates the need for subsequent rotation operations and allows gravity to assist in uniform liquid distribution throughout the channels during the coating process
3Manufacturing precision
If the substrate is held vertically and liquid is continuously introduced by pushing with a piston while applying vacuum to the upper end, then uniform coating is achieved with minimal variation in coating lengths, but the method requires coordinated piston operation and vacuum application which increases control complexity
Solution Approach 1:
The system incorporates feedback through pressure sensors that monitor the pressure differential between the piston and vacuum source. This feedback allows automatic adjustment of piston speed and vacuum intensity to maintain optimal liquid flow rates, ensuring uniform coating without manual intervention or complex coordination
Solution Approach 2:
The invention uses pneumatic-hydraulic coupling where the piston generates pressure to push liquid while the vacuum source creates negative pressure to draw liquid through the channels. The coordinated action of these pneumatic forces, controlled through pressure differential feedback, achieves precise coating control while simplifying the overall system architecture
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach ensures uniform coating with minimal variation in coating lengths, achieving precise control over the coating profile and accommodating a wide range of washcoat viscosities, thereby improving the performance and efficiency of emissions control devices.
Implementation Method 1
introducing the liquid into the substrate by pushing or injecting the liquid with a piston
Implementation Method 2
applying a vacuum to the open ends of the channels at the upper end of the substrate
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A method of coating a substrate with a liquid comprising a catalyst component, which substrate comprises a plurality of channels, wherein the method comprises: (a) holding the substrate vertically; (b) introducing the liquid into the substrate through the open ends of the channels at a lower end of the substrate; and (c) after the lower end of the substrate has been part-filled with the liquid, applying a vacuum to the open ends of the channels at the upper end of the substrate while introducing the liquid into the substrate.